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The Electric Boat Corporation[1] ((EB) is a division of General Dynamics Corporation. It has been the primary builder of submarines for the United States Navy for well over 100 years.

The company's main facilities are a shipyard in Groton, Connecticut and a hull-fabrication and outfitting facility in Quonset Point, Rhode Island.

Contents

History

The company was founded in 1899 by Isaac Rice as the Electric Boat Company in order to build to completion John Philip Holland's submersible designs which were developed at Lewis Nixon's Crescent Shipyard, located in Elizabeth, New Jersey, USA. The first submarine that this shipyard built was (originally) named the Holland VI, later to be known as USS Holland [SS-1]. This was the first submarine to be purchased and commissioned into United States naval service on 11 April 1900. The success of Holland VI ushered in the demand for follow up models (A-class) that began with the proto-type submersible "Fulton" built at the same shipyard where Holland was conceived. Many foreign governments were soon interested in John Holland's latest submarine designs and began purchasing the rights to build them under licensing contracts through Isaac Rice's Electric Boat Company. These governments included Great Britain, Royal Navy; Japan, Imperial Japanese Navy; Russia, Imperial Russian Navy, the Netherlands, Royal Netherlands Navy; and other "civilized" countries.

These new weapons initially devised and developed by the Holland Torpedo Boat Company were now legitimized as genuine naval weapons by the world's most modern industrialized nations during the early part of the 1900s. They were meant to abide by the Hague Conventions of 1899 and 1907, see submarine warfare, but during World War I Germany adopted unrestricted submarine warfare.

During World War I, the company and its subsidiaries built 85 submarines and 722 submarine chasers for the U.S. Navy. After the war the Navy did not order another submarine until 1934. In World War II, the company built 74 submarines.

The firm renamed itself to General Dynamics Corporation in 1952, and when Convair was acquired the next year, the holding company assumed the "General Dynamics" name, with the submarine building operation retaining the "Electric Boat" name. [2]

Electric Boat built the first nuclear submarine, USS Nautilus, which was launched in January 1954, and the first ballistic-missile submarine, George Washington, in 1959, amongst others. Submarines of the Ohio-, Los Angeles-, Seawolf- and Virginia-class submarines were also constructed by Electric Boat.

In 2002, Electric Boat conducted preservation work on the world's first nuclear powered craft, USS Nautilus, preparing her for her berth at the U.S. Navy Submarine Force Museum and Library in Groton, Connecticut, where she now resides as a museum. Electric Boat's first submarine, the USS Holland was unfortunately scrapped for one hundred dollars in 1913.

Electric Boat is also in the business of performing overhaul and repair work on fast attack class boats. Ships that are already built return to Electric Boat's Graving Docks for needed repairs. Electric Boat built the Ohio class fleet ballistic missile submarines and Seawolf class (SSN 21) attack submarines as well as others. However, most of the work done in the ship yard is focused on the new construction of Virginia-class attack submarines.

References

Further reading

  • The Defender: The Story of General Dynamics, by Roger Franklin. Published by Harper and Row 1986. More accurate version of "just who" actually founded this company.
  • Brotherhood of Arms: General Dynamics and The Business of Defending America, by Jacob Goodwin. Published 1985. Random House.
  • The Legend of Electric Boat, Serving The Silent Service. Published by Write Stuff Syndicate, 1994 and 2007. Written by Jeffery L. Rodengen.
  • International Directory of Company Histories Volume 86 under General Dynamics/Electric Boat Corporation, July 2007; pp. 136-139. Published by St James Press/Thomson Gale Group.
  • Who Built Those Subs? Naval History Magazine, Oct. 1998 125th Anniversary issue, pp. 31-34. Written by Richard Knowles Morris PhD. Published by The United States Naval Institute, Annapolis, Md. Copyrighted 1998.
  • The Klaxon, The U.S. Navy's official submarine force newsletter, April 1992. Published by the Nautilus Memorial Submarine Force Library and Museum in Groton/New London, CT.
  • "The Ups and Downs of Electric Boat" John D. Alden, United States Naval Institute, Proceedings Magazine, July 1, 1999, p.64.

External links

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While most boats on the water today are powered by diesel engines, and sail power and gasoline engines are also popular, it is perfectly feasible to power boats by electricity too. Electric boats were very popular from the 1880s[citation needed] until the 1920s, when the internal combustion engine took dominance. Since the energy crises of the 1970s, interest in this quiet and potentially renewable marine energy source has been increasing steadily again, especially as solar cells became available, for the first time making possible motorboats with an infinite range like sailboats. The first practical solar boat was probably constructed in 1975 in England.[1]

Contents

Components

The main components of the drive system of any electrically powered boat are similar in all cases, and similar to the options available for any electric vehicle.

Charger

Electric energy has to be obtained for the battery bank from some source.

  • Mains charger allows the boat to be charged from shore-side power when available. Shore-based power stations are subject to much stricter environmental controls than the average marine diesel or outboard motor. By purchasing green electricity it is possible to operate electric boats using sustainable or renewable energy.
  • Solar panels can be built into the boat in reasonable areas in the deck, cabin roof or as awnings. Some solar panels, or photovoltaic arrays, can be flexible enough to fit to slightly curved surfaces and can be ordered in unusual shapes and sizes. Nonetheless, the heavier, rigid mono-crystalline types are more efficient in terms of energy output per square meter. The efficiency of solar panels rapidly decreases when they are not pointed directly at the sun, so some way of tilting the arrays while under way is very advantageous.
  • Towed generators are common on long-distance cruising yachts and can generate a lot of power when travelling under sail. If an electric boat has sails as well, and will be used in deep water (deeper than about 15 m or 50 ft), then a towed generator can help build up battery charge while sailing (there is no point in trailing such a generator while under electric propulsion as the extra drag from the generator would waste more electricity than it generates). Some electric power systems use the free-wheeling drive propeller to generate charge through the drive motor when sailing, but this system, including the design of the propeller and any gearing, cannot be optimised for both functions. It may be better locked off or feathered while the towed generator's more efficient turbine gathers energy.
  • Wind turbines are common on cruising yachts and can be very well suited to electric boats. There are safety considerations regarding the spinning blades, especially in a strong wind. It is important that the boat is big enough that the turbine can be mounted out of the way of all passengers and crew under all circumstances, including when alongside and when coming alongside a dock, a bank or a pier. It is also important that the boat is big enough and stable enough that the top hamper created by the turbine on its pole or mast does not compromise its stability in a strong wind or gale. Large enough wind generators could produce a completely wind-powered electric boat. No such boats are yet known although a few mechanical wind turbine powered boats exist.
  • If the boat has an internal combustion engine anyway, then its alternator will provide significant charge when it is running. Two schemes are in use: the combustion engine and the electric motor both coupled to the drive, or a separate generator with the combustion engine only charging the storage batteries.

In all cases, a charge regulator is needed. This ensures that the batteries are charged at the maximum rate that they safely can stand when the power is available. It also ensures that they are not overcharged when nearing full charge and not overheated when a large charge current becomes available.

Battery bank

There have been significant technical advances in battery technology in recent years, and more are to be expected in the future.

  • Lead-acid batteries may still be the most viable option at the moment (2008). Deep-cycle, 'traction' batteries are the obvious choice. They are heavy and bulky, but not much more so than the diesel engine, tanks and fittings that they may replace. They need to be securely mounted, low down and centrally situated in the boat. It is essential that they cannot move around under any circumstances. Care must be taken that there is no risk of spilled, strong acid in the event of a capsize as this could be very dangerous. Venting of explosive hydrogen and oxygen gases is also necessary. Typical lead-acid batteries must be kept topped-up with distilled water.
  • Valve-regulated lead-acid (VRLA) batteries, usually known as sealed lead-acid, Gel, or AGM batteries, minimize the risk of spillage, and gases are only vented when the batteries are overcharged. These batteries require minimal maintenance, as they cannot and usually do not need to be refilled with water.
  • Nickel metal hydride, lithium-ion and other solid-state batteries are becoming available, but are still expensive. These are the kind of batteries currently common in rechargeable hand tools like drills and screwdrivers, but they are relatively new to this environment. They require different charge controllers to those that suit lead-acid types.
  • Fuel cells may provide significant advantages in years to come. Today (2008) however they are still expensive and require specialist equipment and knowledge.

The size of the battery bank determines the range of the boat under electric power alone. The speed that the boat is motored at also affects this - a lower speed can make a big difference to the energy required to move a hull. Other factors that affect range include sea-state, windage and any charge that can be reclaimed while under way, for example by solar panels in full sun. A wind tubine in a good following wind will help, and motor-sailing in any wind could do so even more.

Speed controller

To make the boat usable and maneuverable, a simple-to-operate forward/stop/backwards speed controller is needed. This must be efficient—i.e. it must not get hot and waste energy at any speed—and it must be able to stand the full current that could conceivably flow under any full-load condition. One of the most common types of speed controllers uses Pulse-width modulation (PWM). PWM controllers send high frequency pulses of power to the motor(s). As more power is needed the pulses become longer in duration.

Electric motor

A wide variety of electric motor technologies are in use. Traditional field-wound DC motors were and still are used. Today many boats use lightweight permanent magnet DC motors. The advantage of both types is that while the speed can be controlled electronically, this is not a requirement. Some boats use AC motors or permanent magnet brushless motors. The advantages of these are the lack of commutators which can wear out or fail and the often lower currents allowing thinner cables; the disadvantages are the total reliance on the required electronic controllers and the usually high voltages which require a high standard of insulation.

Drive train

Traditional boats use an inboard motor powering a propeller though a propeller shaft complete with bearings and seals. Often a gear reduction is incorporated in order to be able to use a larger more efficient propeller. This can be a traditional gear box, coaxial planetary gears or a transmission with belts or chains. Because of the inevitable loss associated with gearing, many drives eliminate it by using slow high-torque motors. The electric motor can be encapsulated into a pod with the propeller and fixed outside the hull (saildrive) or on an outboard fixture (outboard motor).

Types

There are as many types of electric boat as there are boats with any other method of propulsion, but some types are significant for various reasons.

cruising on the Untersee, a part of Lake Constance. It is based in Radolfzell, Germany.]]
  • Historical and restored electric boats exist and are often important projects for those involved. See the Mary Gordon Electric Boat for example.
  • Canal, river and lake boats. Electric boats, with their limited range and performance, have tended to be used mostly on inland waterways, where their complete lack of local pollution is a significant advantage. Electric drives are also available as auxiliary propulsion for sailing yachts on inland waters.
  • Electric outboards and trolling motors have been available for some years at prices from about $100 (US) up to several thousand. These require external batteries in the bottom of the boat, but are otherwise practical one-piece items. Most available electric outboards are not as efficient as custom drives, but are optimised for their intended use, e.g. for inland waterway fishermen. They are quiet and they do not pollute the water or the air, so they do not scare away or harm fish, birds and other wildlife. Combined with modern waterproof battery packs, electric outboards are also ideal for yacht tenders and other inshore pleasure boats.
  • Cruising yachts usually have an auxiliary engine, and there are two main uses for it: One is to power ahead or motor-sail at sea when the wind is light or from the wrong direction. The other is to provide the last 10 minutes or so of propulsion when the boat is in port and needs to be manoeuvred into a tight berth in a crowded and confined marina or harbour. Electric propulsion is not suitable for prolonged cruising at full power although the power required to motor slowly in light airs and calm seas is small. Regarding the second case, electric drives are ideally suited as they can be finely controlled and can provide substantial power for short periods of time.
  • Diesel-electric. There is a third potential use for a diesel auxiliary and that is to charge the batteries, when they suddenly start to wane far from shore in the middle of the night, or at anchor after some days of living aboard. In this case, where this kind of use is to be expected, perhaps on a larger cruising yacht, then a combined diesel-electric solution may be designed from the start. The diesel engine is installed with the prime purpose of charging the battery banks, and the electric motor with that of propulsion. There is some reduction in efficiency if motoring for long distances as the diesel's power is converted first to electricity and then to motion, but there is a balancing saving every time the wind-, sail- and solar-charged batteries are used for manoeuvring and for short journeys without starting the diesel. There is the flexibility of being able to start the diesel as a pure generator whenever required. The main losses are in weight and installation cost, but on the bigger cruising boats that may sit at anchor running large diesels for hours every day, these are not too big an issue, compared to the savings that can be made at other times.
  • Solar powered. A boat propelled by direct solar energy is a marine solar vehicle. The available sunlight is almost always converted to electricity by solar cells, temporarily stored in accumulator batteries, and used to drive a propeller through an electric motor. Power levels are usually on the order of a few hundred watts to a few kilowatts. Solar powered boats started to become known around 1985 and in 1995 the first commercial solar passenger boats appeared.[2] Solar powered boats have been used successfully at sea. The first crossing of the Atlantic Ocean was achieved in the winter of 2006/2007 by the solar catamaran Sun21.[3][4]

Lifetime pollution and embodied energy

All the component parts of any boat have to be manufactured and will eventually have to be disposed of. Some pollution and use of other energy sources are inevitable during these stages of the boat's life and electric boats are no exception. The benefits to the global environment that are achieved by the use of electric propulsion are manifested during the working life of the boat, which can be many years. These benefits are also most directly felt in the sensitive and very beautiful environments in which such a boat is used.

Solar ship

Japan's biggest shipping line Nippon Yusen KK and Nippon Oil Corporation said solar panels capable of generating 40 kilowatts of electricity would be placed on top of a 60,000 tonne car carrier ship to be used by Toyota Motor Corporation.[5][6][7]

See also

References

External links


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